/*  Starshatter OpenSource Distribution
    Copyright (c) 1997-2004, Destroyer Studios LLC.
    All Rights Reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.
    * Neither the name "Destroyer Studios" nor the names of its contributors
      may be used to endorse or promote products derived from this software
      without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
    LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.

    SUBSYSTEM:    Stars.exe
    FILE:         Shield.cpp
    AUTHOR:       John DiCamillo


    OVERVIEW
    ========
    Weapon class
*/

#include "MemDebug.h"
#include "Shield.h"
#include "Shot.h"
#include "WeaponDesign.h"

#include "Game.h"

// +----------------------------------------------------------------------+

static char*   shield_name[] = {
    "sys.shield.none",
    "sys.shield.deflector",
    "sys.shield.grav",
    "sys.shield.hyper"
};

static int     shield_value[] = {
    0, 2, 2, 3
};

// +----------------------------------------------------------------------+

Shield::Shield(SUBTYPE shield_type)
: System(SHIELD, shield_type, "shield", shield_value[shield_type], 100, 0),
shield_cutoff(0.0f), shield_capacitor(false), shield_bubble(false),
deflection_cost(1.0f), shield_curve(0.05f)
{
    name = Game::GetText(shield_name[shield_type]);
    abrv = Game::GetText("sys.shield.abrv");

    power_flags  = POWER_WATTS | POWER_CRITICAL;
    energy       = 0.0f;
    power_level  = 0.0f;
    shield_level = 0.0f;

    switch (shield_type) {
    default:
    case DEFLECTOR:
        capacity = sink_rate = 2.0e3f;
        shield_factor        = 0.05f;
        break;

    case GRAV_SHIELD:
        capacity = sink_rate = 7.0e3f;
        shield_factor        = 0.01f;
        break;

    case HYPER_SHIELD:
        capacity = sink_rate = 10.0e3f;
        shield_factor        = 0.003f;
        break;
    }

    emcon_power[0] = 0;
    emcon_power[1] = 0;
    emcon_power[2] = 100;
}

// +----------------------------------------------------------------------+

Shield::Shield(const Shield& s)
: System(s), shield_factor(s.shield_factor), requested_power_level(0.0f),
shield_cutoff(s.shield_cutoff), shield_capacitor(s.shield_capacitor),
shield_bubble(s.shield_bubble), deflection_cost(s.deflection_cost),
shield_curve(s.shield_curve)
{
    power_flags  = s.power_flags;
    energy       = 0.0f;
    power_level  = 0.0f;
    shield_level = 0.0f;

    Mount(s);
}

// +--------------------------------------------------------------------+

Shield::~Shield()
{ }

void
Shield::SetShieldCapacitor(bool c)
{
    shield_capacitor = c;

    if (shield_capacitor) {
        power_flags = POWER_CRITICAL;
        shield_curve = 0.05f;
    }
    else {
        power_flags = POWER_WATTS | POWER_CRITICAL;
        shield_curve = 0.25f;
    }
}

// +--------------------------------------------------------------------+

void
Shield::ExecFrame(double seconds)
{
    System::ExecFrame(seconds);

    if (power_level < requested_power_level) {
        power_level += (float) (seconds * 0.10);     // ten seconds to charge up

        if (power_level > requested_power_level)
        power_level = (float) requested_power_level;
    }
    else if (power_level > requested_power_level) {
        power_level -= (float) (seconds * 0.20);     // five seconds to power down

        if (power_level < requested_power_level)
        power_level = (float) requested_power_level;
    }

    if (power_level < 0.01 && !shield_capacitor) {
        shield_level = 0.0f;
        energy       = 0.0f;
    }
}

// +----------------------------------------------------------------------+

void
Shield::Distribute(double delivered_energy, double seconds)
{
    System::Distribute(delivered_energy, seconds);

    if (shield_capacitor) {
        if (shield_cutoff > 0 && shield_cutoff < 0.999) {
            float cutoff = shield_cutoff * capacity;

            if (energy > cutoff)
            shield_level = (energy-cutoff)/(capacity-cutoff);
            else
            shield_level = 0.0f;
        }

        else {
            shield_level = energy/capacity;
        }
    }
    else {
        shield_level = energy/sink_rate;
        energy       = 0.0f;
    }

    if (shield_level < 0)
    shield_level = 0;
}

// +--------------------------------------------------------------------+

double
Shield::DeflectDamage(Shot* shot, double damage)
{
    double filter      = 1;
    double penetration = 5;
    double leak        = 0;

    if (shot)
    penetration = shot->Design()->penetration;

    filter = 1 - shield_factor * penetration;

    if (filter < 0)
    filter = 0;

    else if (filter > 1)
    filter = 1;

    if (shield_capacitor) {
        if (shield_cutoff > 0 && shield_level < 1e-6) {
            leak = damage;
            energy -= (float) (damage * deflection_cost);
        }

        else {
            leak = damage * (1 - pow(shield_level, shield_curve) * filter * availability);

            double deflected = damage - leak;
            energy -= (float) deflected * deflection_cost;
        }

    }
    else {
        leak = damage * (1 - pow(shield_level, shield_curve) * filter * availability);
    }

    return leak;
}

// +--------------------------------------------------------------------+

void
Shield::SetPowerLevel(double level)
{
    if (level > 100)
    level = 100;
    else if (level < 0)
    level = 0;

    level /= 100;

    if (requested_power_level != level) {
        // if the system is on emergency override power,
        // do not let the EMCON system use this method
        // to drop it back to normal power:
        if (power_level > 1 && level == 1) {
            requested_power_level = (float) power_level;
            return;
        }

        requested_power_level = (float) level;
    }
}

void
Shield::SetNetShieldLevel(int level)
{
    if (level > 100)     level = 100;
    else if (level < 0)  level =   0;

    requested_power_level = (float) (level/100.0);
    power_level           = requested_power_level;
}

void
Shield::DoEMCON(int index)
{
    int e = GetEMCONPower(index);

    if (power_level * 100 > e || emcon != index) {
        if (e == 0) {
            PowerOff();
        }
        else if (emcon != index) {
            PowerOn();

            if (power_level * 100 > e)
            SetPowerLevel(e);
        }
    }

    emcon = index;
}
